1. Field of the Invention
The present invention relates to a liquid crystal display driving circuit and method, and more particularly, to a liquid crystal display driving circuit and method, in which a data register block of a controller applies in advance a polarity control signal to data before the data are stored in first latches of a data driver, exchanges the data, and then stores the exchanged data in the first latches, thereby making it possible to provide multiplexers required for respective channels in one controller so that the size of a chip can be decreased.
2. Description of the Related Art
In general, a liquid crystal display (LCD) is one of flat panel displays that adjust light transmittance of liquid crystal cells using optical characteristics of liquid crystal whose molecular arrangement is varied by an electric field, thereby displaying characters, symbols or graphics.
Referring to FIG. 1, a conventional LCD driving circuit 10 supplies scan pulses and data to intersections between data lines and gate lines of a liquid crystal panel having thin film transistors (TFTs) as switching elements for driving liquid crystal cells, and outputs video data. The LCD driving circuit 10 includes a controller 20 which receives video data from a video card, etc., divides the received data into even-numbered data and odd-numbered data and transmits the divided data to latches of respective channels, and a data driver 30 which receives the divided data, latches the received data in response to an enable signal, exchanges data with adjacent channels according to a polarity control signal POL and outputs the exchanged data to data lines.
The controller 20 includes an Rx buffer which receives from the video card, etc. and temporarily stores a low-voltage input signal ‘mini-LVDS (low voltage differential signaling) input data’ as video data to be displayed, and a data register which divides the video data into the even-numbered and odd-numbered data and supplies the divide data to first latches of the data driver 30.
Further, the data driver 30 provided to each pair of channels includes first latches which sequentially sample the video data inputted from the data register in response to a first enable signal ‘1st Latch enable’ generated by a shift register, second latches which latch the data inputted from the first latches and output the latched data in response to a second enable signal ‘2nd Latch enable,’ and multiplexers (MUXes) which select one of a positive polarity gamma voltage and a negative polarity gamma voltage corresponding to respective gray scale values of the video data in response to the polarity control signal POL, exchange the data outputted from the second latches with adjacent channels and then supply the exchanged data to the respective data lines.
In this manner, in supplying the video data to be displayed to the data lines of the liquid crystal panel, the multiplexers for exchanging data with adjacent channels in response to the polarity control signal POL are required. Since the conventional LCD driving circuit receives a current horizontal synchronizing signal of the video data outputted and determines the output polarity of an amplifier provided to a gamma reference voltage generator, the multiplexers should be configured to be connected to the output terminals of the second latches provided to the respective channels through which the video data are output to the data lines.
Accordingly, in the conventional LCD driving circuit, because the multiplexers should be provided to the respective channels, problems are caused in that the size of a region, in which each channel is formed, cannot but be increased, and thus, the size of a semiconductor chip cannot but be increased.